Drying oil and process



Patented Apr. 7, 1942 Ivor M. Colbeth, East Orange, N. 1., The BakerCastor Oil Company,

asslgnor to New York,

N. Y., a corporation of New Jersey No Drawing. Application December 27,1939,

Serial No. 311,121

14 Claims. (01.260-398) This invention relates to products obtained bythe destructive distillation of borated derivatives of hydroxylated longchain aliphatic compounds, and the process of producing such products.It relates more particularlyto the treatment of animal and vegetableoils and thereof in such a way that products result-therefrom that willdry when exposed to the atmosphere. These products can'also bepolymerized by heating them. They may be prepared so as to be liquids ofany desired viscosity ranging from viscosities less than those of theinitial substances from which they are produced to extremely viscousgels.

- This invention is also applicable to the treatment of compounds andcompositions such as animal and vegetable fats, fatty acids and fattyacid esters of mono and dihydric alcohols, as well aspolymerization andoxidation products of the same. This is a continuation-in-part of myapplication Serial No. 209,980, filed May 25, 1938.

A very large number of substances can be used as the starting materials.Among the vegetable oils that can be utilized in carrying out thisinvention are non-drying oils such as castor oil,

semi-drying oils such as soya bean, rape, corn, and cotton seed, anddrying oils such as linseed and perilla. Among the animal oils that aresuit able are whale oil and fish oil, including codliver oil. Amongsuitable fats may be mentioned lard and tallow. Among suitable esters ofmonohydric alcohols are methyl, ethyl and butyl esters derivatives ofstearic, hydroxy stearic, oleic, ricinoleic, and

linolic acids; and among those of dihydric alcohols are the glycolesters of these acids. starting substances used in carrying out thisinvention should contain aliphatic radicals of a sufficient number ofcarbon atoms to afford opportunity for th formation of one or moredouble bonds between carbon atoms.

In my prior Patent 2,125,54 4 of August 2, 1938, I have described howtough resilient products containing boron can be obtained by causingboron compounds to react with certain fatty acid products such as oils,fats,fatty acids, and esters of animal or vegetable origin which containhydroxyl groups, and have pointed out that when these groups were absentthese products could be rendered suitable for making the tough resilientproducts by oxidizing them so as to form hydroxylated groups.

Upon further investigation Ihave found that, if, instead of proceedingas disclosed in my Patent 2,125,544, the liquids to be treated are firstbrought to a temperature of from 260 C. to 300 The 1 C. and maintainedunder a vacuum or atmosphere of inert gas while the boron reagent isadded in small increments allowing the reaction to subside each timebefore further addition of reagent, the resulting product is not a solideven though the quantity of boron had been used which would haveresulted in a solid by my prior process, but is a liquid capable ofabsorbing oxygen and having drying properties.

In carrying out the present invention destructive distillation productsof boron derivatives of hydroxylated aliphatic compounds are obtainedthat have drying properties due to the presence of unsaturated bonds sothat they are suitable for coating purposes and for the production ofvarnishes, lacquers and the like.

Th present invention differs from my prior patent. above referred to inthat the process does not stop when foaming practically ceases and atough resilient product is obtained, but on the contrary furtherreaction of the prior product is caused to take place by destructivedistillation thus forming products which differ decidedly from the toughresilient product in that they are unsaturated liquids having excellentdrying properties.

In this prior patent the reaction with boron is carried on until a toughresilient product is formed. On the other hand, with the presentinvention the reaction with boron is carried on far beyond this in thatdecomposition of the borated product is caused to take place involvingthe removal of hydroxyl groups and the setting up of conjugationeddouble bonds and the formation of estolides.

Furthermore, this same reaction can be availed of in accordance with thepresent invention to v form unsaturated hydrocarbons from saturatedvhydrocarbons, unsaturated alcohols from saturated alcohols, unsaturatedacids from saturated acids, as well as other unsaturated compounds fromthe corresponding saturated compounds. This is'done by first oxidizingthe saturated compound so as to form a hydroxy compound, treating thehydroxy compound with a boron compound capable of reacting with thehydroxyl group, and destructively distilling the borated product. Orsuch oxidizing agents as chlorine, iodine, tc, may be used in theoxidizing step and the hydroxy group may be then formed by treatmentwith alkalis such as aqueous sodium hydroxide. Dilute oxidizing agentssuch as potassium permanganate in alkali solution may be used whendesirable. The resulting products may still contain chemically combinedboron but not all of them necessarily do so since many boron compoundsare volatile and may be removed in the volatile products during theprocess.

In order to enable this invention to be more readily understood I willdescribe what appears to me to be the underlying principle of theinvention, using castor oil as illustrative of the sort of material thatcan be used, and showing how boric acid reacts with it. Since castor oilis made up largely of the glyceride of ricinoleic acid, an hydroxycompound, this compound reacts with boric acid thus:

ROH 0 12011 non .where G represents the glycerine residue and ROI-I thericinoleic acid residue. The molecular weight of castor oil may be takenat 932; that of boric acid as 62. The first step-at the temperature thatis used appears to be the conversion of boric'acid into borlc anhydride:

'rTo

, Reaction of B20: with hydroxyl groups in the place in various wayssuch as:

ricinoleic acid radical in castor oil may take o-non HOR;G

non n The reactions I through III illustrate in each case one mol ofB203. With higher concentrations of B20: numerous combinations andpermutations doubtless take .place whereby enormously large moleculesresult.

In Case I, 1 mol of castor oil reacts with 1 mol of B20: to give aproduct of molecular weight of approximately 976.

In Case II, 2 mols of castor oil react with 1 mol of B10: to give aproduct of molecular weight of approximately 1908.

In Case III, 4 mols of castor oil'react with 1 mol of B20: to give aproduct of molecular weight of approximately 3710.

The final result depends upon the temperature, the percent of B20:present and time of reaction and the reaction from I to III, and,'sincethe physical properties are function of the molecular complexity,the reaction proceeds from liquids through viscous products to gels withincreased time especially rapidly when larger proportions of the boroncompound are used.

Further investigation has shown that it is not necessary to use as largean amount of boron in carrying out the resent invention as is the casewhere a tough solid product is desired. However, it is necessary tofirst form an intermediate viscous product which, when cold, is a gel,and decompose it to form the product of the present invention havingdrying properties.

When the products illustrated in reactions I-HI are heated to veryelevated temperature, say about 300 0., there results a rupture of themolecule at a point adjacent the B linkage which is more clearlyillustrated thus:

The unfinished chain above represents in detail that portion of theradical R in the neighborhood of the boron linkage, the R representingthe other oil molecules in relation to the boron nucleus.

Since boric acid is freed in the reaction described above, it againreacts with unreacted hydroxyls and the reaction proceeds as aboveoutlined, yielding final products that have chemically combined borontherein, The unsaturated products formed further react intermolecularlywith other groups present in the oil toyield estolides.

In the practice of the invention, compounds are formed having dryingproperties due to the presence of numerous double bonds, and at the.same time due to estolide reaction the compounds themselves are ofextraordinarily high molecular weight.

Although the-underlying principle of this invention has been explainedin connection with the treatment of castor oil, it will be understoodthat'aliphatic compounds containing hydroxyl groups or into whichhydroxyls can be introduced at such points thatgthermal decomposition ofthe borated product'will result in unsaturation are also suitable forthis invention. It the compounds already contain conjugated bonds itwould be unnecessary to treat them in accordance with this invention,but if they contain more than one double bond that are not" conjugated,the conjugation of bonds can be efi'ected by this invention. Forexample, linseed oil contains linolic whose double bonds are.unconjugated. v By this invention it is first oxidized to form hydroxylgroups and is then treated as described above. Also, raw castor oil maybe dry distilled at temperatures between 260 C. and

reaction with the oil, borax can first be dissolved in water and thendecomposed with mineral acids and the entire solution gradually fed intothe reacting vessel containing the hot oil. The rapid evaporation of thesolution produces microscopic crystals of boric acid which are morereadily'dissolved by the oil and also facilitates better control of thereaction.

In the case of the use of a semi-drying oil as the starting material thedesired reaction is caused to take place by first oxidizing the oil orotherwise treating it to form hydroxyl groups before treating it with aboron compound. The subsequent reaction with 13203 and the subsequentdecomposition is similar to that already described.

An advantage of-first oxidizing the oil and then reacting it with B20:and the subsequent decomposition is similar to scribed.

An advantage of first oxidizing the oil and then reacting it with B20:and decomposing the boron product is that superor drying properties areobtained and greater resistance to darken- 3 ing or discoloration andgreater alkali resistance are acquired, due to the fact that conjugationof double bonds in the molecules takes place.

It has been found that drying oils produced in accordance with thisinvention, although they may have lower iodine values than naturaldrying oils, dry as .completely and rapidly as the oils are moreunsaturated, probably due to the fact that miscelles, or extraordinarilylarge molecules, are formed which tend to set up gelation in-the film onexposure to air.

Ordinary castor oil can be treated with the gradual addition of from 1%to 7% of boric acid.

The most desirable quantity will depend on the rapidity with "which thereaction takes place,

which, in turn, would depend on the rate of heating or the design of theparticular apparatus used. For instance, with rapid heat transfer,vigorous stirring and provision for foam arresting, the largerpercentages may be used. About 1%,-3% is usually preferable.

The following specific examples of carrying out the invention are givenfor illustrative pur-' poses but it is to be understood that theinvention is not limited to the particular starting materials or detailsmentioned.

Example I Ordinary commercial castor oil is mixed with 1% of boricanhydride acid. The boric acid is dissolved in alcohol or waterand thenadded to the oil. The mixture is heated in a still that is maintainedunder a vacuum of about 25 mm. As the temperature rises, the firstreaction causes the formation of water due to dehydration of the boricacidand the reaction of the resultthat already deing boric anhydridewith the castor oil. The temperature is increased very slowly up toabout 260 C., whereupon the product begins to de- 5 compose and a numberof volatile acids, hep' ldehyde, and water distill from the mixture.After the initial decomposition has begun the temperature is rapidlyincreased to about 300 C. and maintained at the increased temperatureuntil the desired drying qualities have been produced. The temperatureincrement is about 1 C. per minute up to the temperature ofdecomposition, and then about 5 C. per minute to reach the highertemperature desired.

When it is desired toproduce a more viscous oil, this can be done merelyby continuing theheating. In this way the viscosity can be continuouslyincreased until the product is a gel which still has drying properties.the product can be accelerated by the use of driers usually used in thepaint industry.

Example II Soya bean oil is oxidized at 100 C. by means of air until theiodine value has been reduced to 90. The product so formed is treatedwith 3% boric anhydride as described above in Example I. I

' Example II! An aqueous solution of borax containing about 1% of boraxis treated with a sufllcient amount of sulphuric acid to decompose theborax and keep the resulting boric acid in solution. This solution isgradually added to commercial castor oil while it is at a temperature ofabout 260 C., whereupon vigorous reaction takes place. After asuillcient amount of the solution has been added to have present about1% of boron in comparison to the castor oil, the temperature is rapidlyraisedto 300 C. and maintained until the index of refraction of the oilhas reached 1.4820 at 25 C. The resulting product is a light coloreddrying oil.

' Ezrample IV compound the straight chain portion of which contains atleast 6 carbon atoms, said product being unsaturated and having dryingproperties.

3. A destructive distillation residual product of a boron derivative ofa hydroxy aliphatic acid, said product being unsaturated.

4. A destructive distillation residual product of a boron derivative ofa long chain polyhydric alcohol, said product being unsaturated.

5. A destructive distillation residual product of a boron derivative ofan ester of an aliphatic hydroxy acid, said product being unsaturated.

6. A destructive distillation residual product of a boron derivative ofa glyceride of an allphatic hydroxy acid, said product beingunsaturated.

7. A destructive distillation residual product The drying of of a boronderivative of castor oil, said product being unsaturated.

8. The process of treating a hydroxy aliphatic compound with a boroncompound until a boron derivative is obtained, and destructivelydistilling said derivative.

9. The process of treating a hydroxy aliphatic compound the straightchain portion 01' which contains at least 6 carbon atoms with a boroncompound until a boron derivative is obtained, and destructivelydistilling said derivative.

10. The process of treating a hydroxy aliphatic acid with a boroncompound until a boron derivative is obtained,. and destructivelydistilling said derivative.

11. The process of treating a long chain poly- I voR M. COLBE'I'H.

